Method and apparatus for treatment of foliated metallic bearing materials

ABSTRACT

The method of this invention includes the steps of heating and drying foliated metallic bearing materials; classifying the materials into selected size groups by permitting certain of the materials to pass through screens having preselected mesh sizes; selecting certain of the groups and blasting the same at substantially high velocity into a chamber to fracture the foliant matrix of the foliated metallic bearing material, by impinging the sides of the chamber; and separating metallic material from the foliant matrix. The apparatus for treating foliated metallic bearing materials includes the combination of a material reservoir, a blast gun assembly, and a fracture chamber assembly, the blast gun assembly being in communication with the reservoir and in communication with a remote source of substantially hot, dry air under pressure. The blast gun comprises a material chamber issuing into a blast chamber. The material is communicatingly connected to the reservoir by a conduit, and the blast chamber is connected to a remote source of air under pressure. The material is drawn from the reservoir into the material chamber in response to air under pressure in the blast chamber, and is carried by the air under pressure out of the blast chamber. The fracture chamber comprises a top wall, a bottom wall and a pair of opposing side walls, and is disposed distally from the gun assembly. The gun assembly is operable to discharge the material at an angle into one end of the fracture chamber assembly, wherein the fracture assembly is electrically conducting to ground potential. The blast gun assembly is electrically insulated from ground potential.

United States Patent m1 Collins l l METHOD AND APPARATUS FOR TREATMENTOF FOLIATED METALLIC BEARING MATERIALS William 0. Collins, 2255Foothill. Reno, Ney. 89502 [22] Filed: May 14 1973 [2]] Appl. No:359,932

[76] Inventor:

Primary Emmim-rGran\ille Y. ('uster. Jr.

[57] ABSTRACT The method of this invention includes the steps of heatingand drying foliated metallic bearing materials; classifying he materialsinto selected size groups by permitting certain of the materials to passthrough screens ha ing preselected mesh sires: selecting cer- June 10,1975 tain of the groups and blasting the same at substantially highvelocity into a chamber to fracture the foliant matrix of the foliatedmetallic bearing material. by impinging the sides of the chamber; andseparating metallic material from the foliant matrix.

The apparatus for treating foliated metallic bearing materials includesthe combination of a material reservoir, a blast gun assembly and afracture chamber assembly. the blast gun assembly being in communicationwith the reservoir and in communication with a remote source ofsubstantially hot, dry air under pressure. The blast gun comprises amaterial chamber issuing into a blast chamber. The material iscommunicatingly connected to the reservoir by a conduit. and the blastchamber is connected to a remote source of air under pressure. Thematerial is drawn from the reservoir into the material chamber inresponse to air under pressure in the blast chamber. and is carried bythe air under pressure out of the blast chamber. The fracture chambercomprises a top wall. a bottom wall and a pair of opposing side walls.and is disposed distally from the gun assembly. The gun assembly isoperable to discharge the material at an angle into one end of thefracture chamber assembly. wherein the fracture assembly is electricallyconducting to ground potential. The blast gun assembly is electricallyinsulated from ground potential.

7 Claims. 4 Drawing Figures PATENTEDJUH 10 ms SHEET BAA/K RU/V n;METAL/C MATERIAL ASSEMBLY It i K II\ n" V METAL IC PRODUCT MA TERM L FRA CTURE FATENTEDJUN I 0 ms SHEU FIG. 3

METHOD AND APPARATUS FOR TREATMENT OF FOLIATED METALLIC BEARINGMATERIALS FIELD OF INVENTION This invention relates to method andapparatus for treating foliated metallic bearing materials for recoveryof precious metals.

BRIEF DESCRIPTION OF THE PRIOR ART Method and apparatus operable toeconomically separate foliant from metallic particles in foliatedmetallic bearing materials are generally unknown.

The foliated metallic bearing material generally comprises a metallicnucleus surrounded by a foliant. Suffree it to say here that commonlyknown fire or other assay methods are not usually effective to determinethe presence or absence of metals because of the surface tension of thefoliant or metal and the chemical character of the foliant.

The foliant ofthe metallic bearing material generally comprises amultiplicity of alkaline compound. crystallike particles made up chieflyofthe basic alkaline earth family, and includes traces of ferro andtitanic groups adhesively surrounding a metallic particle. Four types offoliants in oxide form have been classified with respect to date offormation and chemical ratio. Generally, all of the alkaline family havean extremely high activity within basic acids. However, the firm form ofoxidation of the foliant material and the chemical com position of thematerial including traces of ferro-titanic oxides appear to limit suchactivity in acids. particularly with respect to the outermost surface ofthe native material in place. Hence, the foliant normally may not beeconomically disolved from about the metallic particle. Although, thealkaline oxide foliant found about such material has an average fracturepoint at about 3,2(J C, such extreme temperatures appear not to beconductive to recovering and separating the metallic material from thefoliant material.

Accordingly, it is an object of the present invention to provide meansby which a foliant may be separated from metallic particleseconomically.

Another object of this invention is to provide apparatus operable tonegatively charge and to discharge foliated metallic bearing material tofracture the foliant entrapped metallic particles.

These and other objects shall become apparent from the descriptionfollowing, it being understood that modifications may be made withoutaffecting the teachings of the invention here set out.

SUMMARY OF THE INVENTION Generally. the method of this inventionincludes the steps of heating and drying foliated metallic bearingmaterials; classifying the materials into selected size groups bypermitting certain of the materials to pass through screens havingpreselected mesh sizes; selecting certain of the groups and blasting thesame at substantially high velocity into a chamber to fracture thefoliant matrix of the foliated metallic bearing material. by impingingthe sides of the chamber; and separating metallic material from thefoliant matrix.

The apparatus for treating foliated metallic bearing materials includesthe combination of a material reservoir, a blast gun assembly. and afracture chamber assembly. the blast gun assembly being in communicationwith the reservoir and in communication with a remote source ofsubstantially hot. dry air under pressure. The blast gun comprises amaterial chamber issuing into a blast chamber. The material chamber iscommunicatingly connected to the reservoir by a conduit. and the blastchamber is connected to a remote source of air under pressure. Thematerial is drawn from the reservoir into the material chamber inresponse to air under pressure in the blast chamber, and is carried bythe air under pressure out of the blast chamber. The fracture chambercomprises a top wall, a bottom wall and a pair of opposing side walls;and is disposed distally from the gun assembly. The gun assembly isoperable to discharge the material at an angle into one end of thefracture chamber assembly, wherein the fracture assembly is electricallyconducting to ground potential. The blast gun assembly is electricallyisulated from ground p0 tential.

A more thorough and comprehensive understanding may be had from thedetailed description of the pre ferred embodiment when read inconnection with the drawings forming a part of this specification.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a flow diagram of methodtaught by the present invention.

FIG. 2 is a fragmentary perspective view of the blast gun assembly andthe fracture chamber assembly of the present invention showing toadvantage the fracture chamber assembly mounted to grounding potentialmeans.

FIG. 3 is a cross-sectional plan view of one type of a foliated metallicbearing material particle drawn to approximately one hundred times itsactual size for illustrative purposes.

FIG. 4 is a cross-sectional plan view of a further known type offoliated metallic bearing material particles.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to thedrawings and more particularly to the FIG. 1, the several steps of theprocess of treatment of foliated metallic bearing materials, as taughtby the present invention. are shown, Native or bank run metallicmaterial as found in its natural environment is put into a rotary kiln,the kiln being of the type and kind commonly known in the art. Foliatedmetallic bearing material is heated to approximately 250 C. in the kiln.The material is discharged from the kiln into a classifier. Materialwhich may not pass through a commonly known size 10 mesh screen isconveyed to a waste or tailings deposit. since it has been found inpractice that particles of this large size do not host metallicmaterials. Materials passing through ll) mesh screens and below arefurther classified into retained size groups ranging from It) to 40mesh, 40 to mesh. 80 to I50 mesh, and below I50 mesh. Materials belowmesh, retained upon a screen of that size, have been found to hostnominal quantities of metals which may not be economically recovered byknown pro cesses. Hence, such material is conveyed to the tailingsdeposit without further treatment. The several classified materialgroups of l0 to 40 mesh, 40 to 80 mesh. and 80 to 150 mesh arepreferably each conveyed to separate material fracture assemblies of thetype and character hereinafter later described.

The steps of the process required of a material fracture assembly meansinclude negatively. electrically charging the dry. heated particles offoliated mctalic materials statically, blowing the particles withsubstantially dry air under pressure from a remote source against anelectrically conducting plate. and statically discharging the particlesby raising the potential of the particles to ground potential whencontacting the plate. and, further. causing the particles torepetitively impinge the plate with sufficient force to fracture thefoliant material surrounding such particles. Suffice it to say thatparticles tend to become statically negatively charged in the hot dryair of a rotary type kiln since the more positive protons tend to bedislodged from the particles as they cascade in the drum in response torotation of the kiln. Some advantage has been noted when apparatus iselectrically insulated to the impingement in the fracture chamberhereinafter later described. in practice, it has been found that theparticles of retained classified material groups on the order of l tomesh, 40 to 80 mesh, and 80 to lSO mesh tend to become more uniformlycharged separately in groups. than do particles of a conglomerate massof foliated metallic bearing materials having all of the processablesizes above described.

Referring now to the FIGS. 3 and 4, a cross-section of each of two typesof foliated metallic materials are shown in the respective drawings.Such materials have been found and identified in vast quantities inancient trenches throughout the western portion of the United States. Tobetter understand the processes and apparatus of this invention, anunderstanding of the nature of material may here be set out, because ofthe lack of data and knowledge concerning such material in the priorart. Although gold (A.,) shall herein become descriptive of the metallicsubstance. it is to be understood that such material does, in fact, hostother precious metals. For convenience, the material of FIG. 3 is hereinidentified as Phase Ill metal; the metal of FIG. 4 being identified asPhase II metal, which identification is in concert with theidentification classifications of free gold and Phase 1 gold hosted in ahard rock matrix in layers. Phase ll and Phase III metals differ only inthat Phase ll metals include a matrix coating in addition to thefoliant. and the metal particle is usually spherically shaped. That isto say that foliated metallic material generally comprises a metallicnucleus surrounded by a foliant. Suffice it to say here that commonlyknown fire or other assay methods are not usually effective to determinethe presence or absence of metals because of the surface tension of thefoliant or metal and the chemical character of the foliant.

The foliant of the metallic bearing material generally comprises amultiplicity of alkaline compound, crystallike particles made up chieflyofthc basic alkaline earth family. and include traces of fcrro andtitanic groups adhesively surrounding a metallic particle. In thedrawings. the foliant crystaklike particles are identified by the letterF. while the metallic particle is identified All- Four types of foliantsin oxide form have been classified with respect to date of formation andchemical ratio. Generally, all of the alkaline family have an extremelyhigh activity within basic acids. However. the firm form of oxidation ofthe foliant material and the chemical composition of the foliantmaterial including traces of fcrro-titanic oxides appear to severallylimit such activity in acids. particularly with respect to the tilloutermost surface of the native material in place. Hence. the foliantnormally may not be economically disolved from about the metallicparticle. By experimentation, the alkaline oxide foliant found aboutsuch material has an average fracture point at about 3,200 C. However,such extreme temperatures appear not to be conducive to recovering andseparating the metallic material from the foliant material.Experimentation also indicates that alkaline family foliant tends to bemore negatively charged than the metallic particles to which they areattached. That is to say there appears to be an electrically staticsurface tension between the metallic particle and the foliant material.In practice, it has been found that. when the hot dry material isturbulatcd in a chamber. the material tends to become electrically alesser potential; and that, when such particles contact an electricallygrounded plate, the foliant ma terial tends to fracture or break about aline distally from the metallic particle. Such fracture line is generally shown in the drawing by the broken line. Additionally, surfacetension between the foliant and metallic particles tends to besignificantly reduced so that further, additional impingement of theparticles on the plate tends to cause the foliant particles to be brokenaway from the metallic particles. With the outermost surface barrierbroken away. the foliant tends to be more soluable, and may then bewashed" from the metallic particle. Suffice it to say that the matrixcoating about metallic particles of Phase Il material generallycomprises alluvial matter which is soluable in water.

It should be pointed out that it has been found in practice that thenatural material from its native environment has a specific gravity of3.5; that the gold has a specific gravity of 17; that the foliantmaterial has a specific gravity of 2; and that material fractured by theprocess above described has a resulting specific gravity of between 6and 7.

Referring again to the flow diagram of the FIG. 1, fractured foliantmetallic material is discharged from the material fracture assembly intoa commonly known combination agitating-slurry classifier, preferably ofthe liquid (water! flotation type. in practice, it has been found thatmore violent agitation of the material tends to cause a greaterproportion of foliant material and matrix material to be separated fromthe metallic material. [t is to be understood that any of a variety ofindependent separators and classififers may be used and employed toaccomplish the steps of separating the metallic material and the foliantand matrix materials and in classifying the respective materials. Thesize classitied materials are then conveyed to a commonly knownconcentrator to separate the metallic materials from other materials.

Referring to the FIG. 2, the material fracture assembly of the presentinvention is generally shown and identified by the numeral 10. Thematerial fracture as sembly includes a material reservoir 1], a blastgun assembly 12 in communication with the reservoir 11. and a fracturechamber 13 carried by a framework 14 mounted to a floor 15 in contactwith original ground. The blast gun assembly 12 is distally disposedfrom the fracture chamber 13. The gun assembly 12 includes a turbulatingmaterial chamber 16 and a blast chamber 17, the blast chamber 17 beingconnected to a suitable remote source of air under pressure. Foliatedmetallic material tends to be drawn into the turbulating chamber 16 byvacuum pressure of the air passing through the blast chamber 17 of thegun assembly [2. ln practice it has been found that hot dry foliatedmetallic material tends to be negatively electrically charged byturbulent movement within the turbulating chamber l6. When the materialis blasted from the blast chamber 17 into the fracture chamber 13 inresponse to air under pressure. its electrical potential tends to beraised to ground potential since the fracture chamber 13 is incommunication with the ground through the floor 15 and the framework 14.It has also been found that the foliatcd material about the metallicmaterial tends to fracture. and surface tension between the foliantmaterial and the metallic material tends to be significantly reduced ashercinbeforc described in response to contact of the foliated metallicmaterial with the fracturc chamber I3. It has further been found thatinitial engagement with the chamber 13 mcrcly causes fracture andrelease of surface tension regardless of force of the impinging materialagainst the plates or walls of the fracture chamber 13. Therefore. ithas been found to advantage to cause the material to repeatedly impingethe chamber [3 to break away foliant material from metallic material.For this reason the blast gun assembly I2 is preferably disposed at anangle to the fracture chamber 13. and has been found most effective whendisposed at an angle less than 45.

The fracture chamber l3. shown to advantage in the FIG 2. preferably isprovided with a substantially flat top wall plate 18. a pair of opposingsidewalls l9 and 19'. and an inverted. substantially shaped bottom wallwhich deflects thc foliant metallic material.

In operation. substantially dry. heated foliatcd metallic material isdrawn from the reservoir I into the turbulating chamber 16 in responseto air under pressure being introduced into the blast chamber 17 from aremote source. The material is then conducted into the blast chamber 17.and blown against the plate 18 of the fracture chamber 13. The materialsuccessively impinges the walls l8. l9. l9 and 20: and is ultimatelydischarged from the fracture chamber [3 at the end oppositc the blastgun assembly 12.

Having thus described in detail a preferred apparatus which embodies theconcepts and principles of the invention and which accomplishes thevarious objects. purposes and aims thereof. it is to be appreciated andwill be apparent to those slyillcd in the art that many physical changescould be made in the apparatus without altering the inventive conceptsand principles embodied therein. Hence. it is intended that the scope ofthe invention be limited only to the extent indicated in the appendedclaims.

I claim:

I. The method of treating foliatcd metallic bearing materials comprisingthe steps of heating and drying foliated metallic bearing materials.

classifying said materials into selected size groups by permittingcertain of the materials to pass through screens having severalpreselected mesh silcs of It) mesh to mesh.

selecting one of said sized groups and blasting said group atsubstantially high velocity into a chamber to fracture the foliantmatrix of said foliatcd metallic bearing material. by impinging thesides of said chamber.

separating metallic material from said foliant matrix.

2. The method of claim 1 involving the steps of heating foliatedmetallic bearing material to approximately 250 C.

3. The method of claim 1 including the steps of agitating said materialwith substantially hot. dry air under pressure from a remote source whenblasting said selected materials into said chamber to electricallystatically negatively charge said selected materials before impingingsaid sides of said chamber. said chamber being electrically connected toconduct to ground potential.

4. In an apparatus for treating foliatcd metallic bearing materials thecombination of a material reservoir. a blast gun assembly. and afracture chamber assembly. said blast gun assembly being incommunication with said reservoir and in communication with a remotesource of substantially hot. dry air under pressure. said blast guncomprising a material chamber issuing into a blast chamber. saidmaterial chamber being communicatingly connected to said reservoir by aconduit. said blast chamber being connected to said remote source of airunder pressure. said material being drawn from said reservoir into saidmaterial chamber in response to air under pressure in said blastchamber. said material being carried by said air under pressure out ofsaid blast chamber. said fracture chamber comprising a top wall. abottom wall and a pair of opposing side walls and being disposeddistally from said gun assembly. said gun assembly being operable todischarge said material at an angle into one end of said fracturechamber assembly. said fracture assembly being mounted electricallyconducting to ground potential. said blast gun assembly beingelectrically insulated from ground potential.

S. The apparatus ofclaim 4 in which said bottom wall of said fracturechamber is substantially \'-shaped.

6. The apparatus of claim 4 in which said blast chamber of said blastgun assembly is disposed at an angle to the top wall of said fracturechamber assembly.

7. The apparatus ofclaim 6 in which said blast chantber of said blastgun assembly is disposed at between approximately 30 and 45 to said topwall of said fracturc assembly.

1. THE METHOD OF TREATING FOILATED METALLIC BEARING MATERIALS COMPRISINGTHE STEPS OF HEATING AND DRYING FOLIATED METALLIC BEARING MATERIALS,CLASSIFFYING SAID MATERIALS INTO SELECTED SIZE GROUPS BY PERMITTINGCERTAIN OF THE MATERIALS TO PASS THROUGH SCREEN HAVING SEVERALPRESELECTED MESH SIZES OF 10 MESH TO 150 MESH,
 2. The method of claim 1involving the steps of heating foliated metallic bearing material toapproximately 250* C.
 3. The method of claim 1 including the steps ofagitating said material with substantially hot, dry air under pressurefrom a remote source when blasting said selected materials into saidchamber to electrically statically negatively charge said selectedmaterials before impinging said sides of said chamber, said chamberbeing electrically connected to conduct to ground potential.
 4. In anapparatus for treating foliated metallic bearing materials thecombination of a material reservoir, a blast gun assembly, and afracture chamber assembly, said blast gun assembly being incommunication with said reservoir and in communication with a remotesource of substantially hot, dry air under pressure, said blast guncomprising a material chamber issuing into a blast chamber, saidmaterial chamber being communicatingly connected to said reservoir by aconduit, said blast chamber being connected to said remote source of airunder pressure, said material being drawn from said reservoir into saidmaterial chamber in response to air under pressure in said blastchamber, said material being carried by said air under pressure out ofsaid blast chamber, said fracture chamber comprising a top wall, abottom wall and a pair of opposing side walls and being disposeddistally from said gun assembly, said gun assembly being operable todischarge said material at an angle into one end of said fracturechamber assembly, said fracture assembly being mounted electricallyconducting to ground potential, said blast gun assembly beingelectrically insulated from ground potential.
 5. The apparatus of claim4 in which said bottom wall of said fracture chamber is substantiallyV-shaped.
 6. The apparatus of claim 4 in which said blast chamber ofsaid blast gun assembly is disposed at an angle to the top wall of saidfracture chamber assembly.
 7. The apparatus of claim 6 in which saidblast chamber of said blast gun assembly is disposed at betweenapproximately 30* and 45* to said top wall of said fracture assembly.